1. Field
Embodiments described herein relate generally to a battery monitoring circuit and a battery monitoring system.
2. Background Art
A battery monitoring circuit that detects abnormality of each voltage of plural secondary cells that are used for batteries of hybrid cars and electric vehicles (EVs) and are connected in series is known.
For example, the battery monitoring circuit according to the related art is configured by using two sets of switch groups to select voltages of terminals between cells and connecting one of the switch groups to one end of a capacitor and connecting the other switch group to the other end of the capacitor.
According to the operation of the battery monitoring circuit according to the related art, first, upper and lower terminals of target cells are connected to both ends of the capacitor to equalize a voltage between the terminals of the capacitor to a cell voltage. Next, after the capacitor and the two switch groups are disconnected and both ends of the capacitor are opened, using a set of switches to be separately prepared, one end of the capacitor is connected to a reference voltage of an A/D converter and the other end of the capacitor is connected to an input of the A/D converter, and the cell voltage is measured.
By sequentially performing a series of operations of the battery monitoring circuit according to the related art on the target cells, voltages of all of the cells can be measured.
However, in the battery monitoring circuit according to the related art, the two sets of switch groups need to be provided to select the voltages of the terminals between the cells and a circuit scale increases. Further, one set of switches need to be provided between the capacitor and the A/D converter.
That is, a manufacturing cost of the battery monitoring circuit increases.